The present invention relates to a remover solution for resist or, more particularly, to a remover solution which can be used with stability in the removing works of resist in the manufacturing process of semiconductor devices without the disadvantage of formation of insoluble matters even when the solution is used in a continuous removing treatment of resist.
As is well known, the manufacturing process of semiconductor devices such as ICs and LSIs generally involves the successive steps in which a substrate of, for example, semiconductor silicon wafer is first provided on the surface with a thin film such as oxide film, then the surface is coated uniformly with a resist in the form of a solution to form a resinous layer sensitive to actinic rays, the resist layer is exposed pattern-wise to actinic rays followed by a development treatment to form a patterned resist layer, the underlying thin oxide film is subjected to pattern-wise etching with the patterned resist layer as the mask against etching and finally the patterned resist layer is removed completely. The resist having sensitivity to actinic rays implied in the present invention include photoresists, electron-beam resists, X-ray resists and the like.
The above mentioned last step of removal of the resist is performed conventionally by using an inorganic remover liquid such as hot concentrated sulfuric acid, fuming nitric acid, mixture of sulfuric acid and hydrogen peroxide and the like. These remover liquids are of course very dangerous to the human body and the danger is increased greatly when the remover is used at a high temperature requiring utmost care in handling of the remover. Moreover, these strongly acidic removers have a disadvantage that not only the patterned resist layer is removed thereby but also the underlying metallic layer which should not be dissolved away is not safe from the attack by the remover. In this regard, it is a trend in recent years that the inorganic removers are increasingly replaced with an organic remover formulated by using various organic solvents.
Various types of organic remover solutions have been proposed including mixtures of organic solvents such as phenol, halogenated hydrocarbon solvents and the like and a surface active agent such as alkylbenzene sulfonic acid and the like, mixtures of an alkylbenzene sulfonic acid of which the overall number of the carbon atoms in a molecule is 10 to 20 and a nonhalogenated aromatic hydrocarbon solvent having a boiling point of 150.degree. C. or higher as disclosed in Japanese Patent Kokai 51-72503 , mixtures of a surface-active alkyl aryl sulfonic acid of which the overall number of the carbon atoms in a molecule is 10 to 20, a hydrotropic aromatic sulfonic acid of which the overall number of the carbon atoms in a molecule is 6 to 9 and a non-halogenated aromatic hydrocarbon solvent having a boiling point of 150.degree. C. or higher as disclosed in U.S. Pat. No. 4,165,294, polar or non-polar organic solvents admixed with effective amounts of 1,2-dihydroxy benzene and an organic sulfonic acid as disclosed in European Patent Publication No. 01 19 337, mixtures composed of 30 to 70% by weight of one, or a combination of aromatic hydrocarbons having a flash point of 70.degree. C. or higher containing at least 50% by weight of one or more of naphthalene compounds including naphthalene, methyl naphthalene and dimethyl naphthalene, 5 to 40% by weight of one or more of phenol compounds and 10 to 50% by weight of an aryl sulfonic acid as disclosed in Japanese Patent Kokai 62-35357, and so on.
These organic remover solutions are more and more widely used in recent years replacing conventional inorganic ones by virtue of their advantages that they are less dangerous than inorganic ones and have an excellent corrosion-preventing activity for layers of a metal such as aluminum formed on the substrate. When such an organic remover solution is used continuously at a high temperature of, for example, 100 .degree. C or higher as is usually the case in order to obtain a removing activity suitable for practical use in the removing treatment of a resist, a disadvantage is sometimes caused that insoluble matters are precipitated in the remover solution and deposited on the substrate surface. Accordingly, it is not a sufficient condition for a remover solution that the patterned resist layer can be completely removed from the substrate surface thereby but it is essential that no insoluble matters are deposited on the substrate surface since otherwise the remover solution cannot be used in practice due to lack of stability.